Abstract

The paper is divided in two parts. Part one describes the Stent Automatic Pile Positioning and Recording system (SAPPAR) which was launched in November 1994. The system utilises a Trimble satellite global positioning system (GPS) to assist rig drivers in accurately positioning the rig over a pile position without the need for setting out. Advantages of the system include: cost savings by removing the need for site survey staff; faster set-up times over pile positions; increased accuracy — the system can reliably position the rig to within ± 25 mm; removal of problems resulting from damage to setting out pins; constant monitoring of pile position; and Links to CAD for data input and as-built drawings. Part two describes a further development of the system in collaboration with Lancaster University and Casagrande, the Italian rig manufacturer. The aim of the research is to fully automate the final positioning process. This represents one of the first uses of GPS for real-time automation. The system hardware components include: ultra-compact PC1O4 processor cards for a compact and robust embedded system; minimum sensing on the rig to minimise cost and maximise robustness; and limit sensors to facilitate on-board safety. The control algorithms were developed on a fifth-scale model in the laboratory using an innovative and new approach to the design of model based control systems. The importance of careful consideration of safety issues is stressed and conclusions are drawn based on the early findings from preliminary field trials.